Step 1: Wash and thinly slice the English cucumber. Lay the slices on paper towels, sprinkle lightly with salt, and let sit for 10-15 minutes to draw out excess moisture. Gently blot dry with more paper towels.
Step 2: In a medium bowl, combine the softened cream cheese, mayonnaise, chopped dill, chives, parsley, garlic powder (if using), salt, and pepper. Mix well until smooth and thoroughly combined.
Step 3: Lay out the slices of white bread. Carefully trim off all the crusts using a sharp knife.
Step 4: Spread a generous, even layer of the herbed cream cheese mixture onto one side of each bread slice, extending to the edges.
Step 5: Arrange the dried cucumber slices in a single layer over half of the cream cheese-covered bread slices, slightly overlapping them to cover the surface.
Step 6: Place the remaining cream cheese-covered bread slices on top of the cucumber-layered ones, cream cheese side down. Gently press down to secure.
Step 7: Using a very sharp knife, cut each assembled sandwich into desired shapes. Traditionally, they are cut into four triangles (by cutting diagonally twice) or three rectangles (finger sandwiches).
Step 8: Serve immediately or cover with a damp paper towel and then plastic wrap, refrigerating until ready to serve to prevent drying out. Best consumed within a few hours.